The Art of Astrophotography

Today we are going to try to break down a very big, very
complex topic. One that, quite literally spans the universe: astrophotography.
I’ve been noticing Fred Herrmann’s images for a while now, he is one of our
most active photographers on Your Shot. I realized when it came to
astrophotography I knew very little about what I was looking at or how these
images were made. So, I called up Fred who helped me to understand I’m not the
only one sometimes overwhelmed by the size of our universe.

Fred Herrmann

To me, the sizes, the distances and the times involved in
astrophotography, and you know cosmology in general, are just, to me, humanly
incomprehensible.

Marie

These spaces and sizes are so big that, by the time the
light reaches Fred’s telescope these objects can be thousands of years old.

Fred

As an astronomer you are a time traveller.

Marie

During his time at NASA he became a diver and helped train
astronauts in the Neutral Buoyancy Simulator. It’s the largest indoor body of
water in the world. This is a place where astronauts can simulate being without
gravity. It helped them train for things like the repair of the Hubble
telescope.

He worked for NASA for about 30 years, and upon retiring he
built an observatory in his own backyard!

Fred

I used to call it the “Robodome” because, it’s basically a
robot, if you would.

Marie

Now, Fred will be the first to tell you, looking through a
telescope is not nearly the same as producing these deep space images. Our eyes
simply cannot see the colors that astrophotography brings to life. There are
two main reasons for this, the first is our eyes cannot process a large portion
of the light spectrum to bring out the colors that are there. And the second
reason is, well, our pupils are not 12 inches in diameter.

Fred

The pupil size determines how much, or, how many photons
that your light can actually collect of a particular object.

Marie

Yeah, how much light we are letting in.

Fred

Exactly. So what we end up doing is, when we’re using a
telescope we are basically, effectively, increasing our pupil size.

Marie

So, how are these brilliant colors brought out? As Fred
explained to me, each pixel on a color chip is divided into four parts- a red,
a blue and two green. Now, the problem here is there is very little green in
astrophotography. So by shooting on a color chip, essentially half your card is
attempting to record colors that aren’t there.

For this reason, Fred actually shoots with a monochrome
chip.

Fred

A typical image will be an R- a red, green blue image, an RGB
image. And what you end up doing is you rotate- and this is all built into the
camera- you rotate the filters in front of the sensor. So after you’ve done
your red, your green, and your blue exposures, those exposures are then
combined into a color image analogous to the way that they made the old Technicolor
movies such as the Wizard of Oz movie.

Marie

Scientists who use the Hubble telescope are often mapping
different colors to different gases, like sulfur, hydrogen and oxygen, to
better understand what these objects are actually made of. The way Fred uses
RGB filters, he is bringing out the, quote on quote, “true colors” of each
object.

Fred

It’s very easy to basically go overboard and, you know, over
process the image. And at that point- you begin to basically lose the
organicness- if you would- of the image very quickly.

Marie

These nebulas and supernovas and other galaxies you’re
looking into- they’re in the past, right? You’re looking into the past.

Fred

Absolutely, yeah. What you have to consider is that, the
photons that you collected that night, or the photons I collected say in 2011
for that gif animation, those photons were actually emitted from the stars
surrounding M-1 and the emission nebula, 5,000 years ago. So at the time that
those photons actually left the molecular clouds, or the stars in that image,
Moses was wandering around the Sinai desert somewhere. Which is pretty
incredible, when you think about it. Because, ya know, when you start thinking
of biblical events like Moses and things like that, I mean, that to us is
ancient history!

Marie

You’ve mentioned that you think this is an art you can never
perfect and there are clearly enough objects out there that you could do this
every day for a million years and not finish. So, what keeps you doing this
every night? What’s the ultimate goal?

Fred

I just enjoy the aesthetics of producing appealing,
aesthetic images. Sometimes I am interested in some of the science behind the
object, but for the most part, I just enjoy the beauty of the universe.

Marie

Wow, well this has been fascinating. If you’d like to learn
anymore about the images you saw here today, please go on and visit Fred’s Your
Shot page. Thanks for listening!